This invention relates to an apparatus for treating yarn with a pressured fluid in a jet. More particularly, it concerns a baffle and deflector arrangement at the outlet end of a yarn texturing jet.
Fluid jet processes are known for texturing or bulking yarn that employ both movable and fixed baffles positioned at various distances from the outlet end of the jet and at various angles to the yarn path to deflect yarn and fluid from a straight path as they leave the jet.
In making a yarn having crunodal loops, the texturing jet must forward the overfed yarn under sufficient tension to keep the yarn from wrapping on the feed rolls, and this tension is provided by the drag of the pressurized air which is moving much faster than the yarn. The air opens the yarn, whips the filaments about, forms loops in the filaments, then entangles them together into a structure which can retain the loops under the tensions which such yarns encounter when made into fabrics. The tension must be low at the jet exit to accumulate loops and form the entangled structure. Immediately thereafter, higher tension is desired to tighten the entangled structure and stabilize it.
A baffle against which the air and yarn impinge is often provided at the jet exit to provide a controlled air zone and to change the direction of yarn movement abruptly. Such baffles are especially necessary at high texturing speeds and air pressures. However, with known cylindrical baffle arrangements, the air divides around the baffle, and the portion of the air which follows the yarn continues to exert tension.
In the present invention, the majority of the air follows the lower surface of a baffle while the yarn moves around the lower surface of the baffle.
Wind-up tension is a good measure of texturing jet effectiveness in converting filamentary bulking overfeed into loops, which are well consolidated and integrated with each other into a stable and coherent yarn bundle. Good wind-up tension also yields a firm, rather than soft/mushy, textured yarn package. Yarn withdrawal from such firm packages is easy and uniform, without snags and tangles associated with soft, mushy packages.
High wind-up tension in texturing also yields packages with yarn that resists bulk pull-out in subsequent high tension operations, such as warping, tufting or knitting. Poor loop consolidation into the yarn bundle, as evidenced by low wind-up tension, is also undesirable in the finished fabric or carpet. Abrasion on the surface of such fabrics, during use, will generally yield plucked-filaments, scuffing, fuzzing and unattractive appearance in relatively short time. Yarns with well consolidated loops, integrated into a compact yarn bundle, generally resist scuffing and fuzzing longer when converted to fabrics or carpets. Texturing tension is measured post jet, and wind-up tension is measured pre-packaging. There is a parallel relationship between texturing tension and wind-up tension, although the former is generally much lower in magnitude than the latter. Yarns with low texturing tensions show low wind-up tensions, while yarns with high texturing tensions also show wind-up tensions in the high range.
With the present invention, textured yarn wind-up tension increases by a surprising amount, reaching 20 to 100% more than wind-up tension realized under similar conditions with jets of the prior art, such as Agers U.S. Pat. No. 4,157,605.
SUMMARY OF THE INVENTION
A yarn treating jet is modified to provide a baffle at its outlet end. The baffle has a peripheral surface wherein that portion of the surface nearest the outlet end is spaced from the outlet end a distance of from 0.1 to 2.0 minimum diameters of the bore of the jet, measured downstream of the location in the jet bore where the air impacts the yarn, and that portion of the surface nearest the central axis of the jet is spaced a distance above the central axis of from 0.1 to 3.0 of said minimum diameters. The baffle may have a circular, curvilinear or polygon cross section.